The Effects of Highways on Guanaco Movement in Patagonia

Research Questions:

  1. How do highways impact guanacos’ movement?

  2. Do guanacos respond differently to roads with varying traffic volumes?

Hypothesis and Predictions

I hypothesize that guanaco movement will be impacted by the highway and that guanancos will avoid crossing roads with high traffic.

  • Guanacos are less likely to cross the highway
  • Guanacos will be more likely to cross at night since they are more active
  • Female guanacos will be less likely to cross the highway since they often have chulengos (baby guanacos)

Study Area

Code
rutas <- st_read("/Users/zoefairlie/Desktop/Thesis/rutas_all_roads.shp", quiet = TRUE)
highway <- st_read("/Users/zoefairlie/Desktop/Thesis/highway.shp", quiet = TRUE)
tourist <- st_read("/Users/zoefairlie/Desktop/Thesis/caminos2.shp", quiet = TRUE)
park_roads <-st_read("/Users/zoefairlie/Desktop/Thesis/park_roads.shp", quiet = TRUE)

tourist <- st_transform(tourist, st_crs(highway))
park_roads <- st_transform(park_roads, st_crs(highway))

road_data = highway %>% mutate(type = 'Highway') %>% select(type) %>%
  rbind(tourist %>% mutate(type = 'Visitor Road') %>% select(type)) %>%
  rbind(park_roads %>% mutate(type = 'Park Roads') %>% select(type)) %>%
  st_cast("LINESTRING")  %>%
  st_as_sf() %>%
  group_by(type) %>%
  summarise(geometry = st_union(geometry))
st_as_s2(): dropping Z and/or M coordinate
st_as_s2(): dropping Z and/or M coordinate
Code
map_tile <- annotation_map_tile(type =
    paste0('https://services.arcgisonline.com/arcgis/rest/services/NatGeo_World_Map',
                '/MapServer/tile/${z}/${y}/${x}.jpeg'),
  zoom = 9,
  cachedir = "tile_cache",
  alpha = .7)


ggplot(data = road_data) +
  map_tile +
  geom_sf(data = road_data, aes(color = type,size = type), alpha = 0.6, show.legend = "line") +
    scale_color_manual(name = 'Road Type',
    values = c('Highway' = '#d95d67', 'Visitor Road' = '#ff9e4d',
                                'Park Roads' = '#A9866D')) +
  scale_size_manual(name = 'Road Type',
                    values = c('Highway' = 2, 'Visitor Road' = 1,
                                'Park Roads' = .5))+
  # geom_point(aes(x = Longitude, y = Latitude), shape = 16, alpha = .3) +
  # scale_color_manual(name = 'id',
  #                   values = color_pal[1]) +
  #geom_path(data = test, aes(x = Longitude, y = Latitude)) +
  # scale_colour_manual(name = "Bird ID",
  #                     values = rainbow(length(unique(tracksgeo$id))),
  #                     breaks = unique(tracksgeo$id)) +
  coord_sf() +
  theme_void() +
  theme(legend.position = 'right',
    panel.grid = element_blank())
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Differences in Road Crossings by Road Type

Note: Guanaco data spans from October 2019 through November 2021.